Hammermills of the type contemplated herein are widely used to reduce metal objects, such as cars, into small metal fragments by the rotation of a hammer assembly within the housing of the hammermill. A hammermill of this general type is shown in U. S. patent application Ser. No. 07/554,139, filed on Jul. 16, 1990, entitled, "Heavy Duty Spider Assembly For A Hammermill," and assigned to the same assignee. The assembly disclosed in this application is formed by a number of six arm spiders which are axially aligned on the hammermill shaft for rotation within the hammermill housing. A number of hammers are randomly mounted on the various spider arms which are spaced apart by spacers located on the hammermill shaft.
The hammermill as described above is used to shred heavy metal scrap, commonly denominated No. 2 scrap. The spider arms are spaced apart around a hub portion with the hammers located in the spaces between the spider arms. End caps are provided on the ends of the spider arms for absorbing the impact of shredded pieces with the outer ends of the spider arms to thereby extend the life of the spiders.
In U.S. Pat. No. 4,613,088, issued on Sep. 23, 1986, and entitled, "Arrangement For Reinforcing And Spacing Annular Disks Of A Hammer Rotor," a hammermill is disclosed wherein the discs are equally spaced along the hammermill drive shaft with the hammers mounted between the discs on hammer pins at various positions within the hammer assembly. The edges of the discs are covered by replaceable strips which provide a shield to protect the outer periphery of the discs and thereby prevent wear due to impact with the heavy metal scrap. In this type of a hammermill the hammers rotate through openings in the shield, thus providing impact only on engagement of the hammers with the heavy metal scrap. However, loose pieces of scrap can be pulled into the hammer assembly and retained therein by the shield.